Being a rotary machine, wind turbine generators (WTG's) are subject to cyclical loads and stress variations over long periods. Vibration from this cyclical variation may result from the rotor, rotor shaft, shaft bearings or other components of the WTG.
Whilst vibration within a wind turbine generator will occur during normal operating conditions, it is of concern if this vibration approaches the resonant frequency for any particular component of the WTG assembly. Under normal operating conditions or under anticipated variations to normal operating conditions, measures can be taken to address the potential for resonance through varying the moment of inertia of the rotor and/or nacelle. Further, dampening systems can be incorporated into the assembly at strategic locations about the nacelle.
Unfortunately, should an unanticipated event occur and the system approach a resonant frequency, significant damage can occur in a very short space of time. Further, many of the conventional sensors on the wind turbine generator, such as rotor speed, the shaft speed, power output etc, may not register a fault until significant damage has occurred. Consequently, the speed of response to an adverse sensor reading may be too slow to react to excessive vibration.
It is therefore an object of the present invention to provide a means by which vibration can be measured and acted upon before significant damage occurs.